1. Field of the Invention
This invention relates to a thermosetting highly foaming sealer for filling and sealing gaps. The thermosetting highly foaming sealer foams and fills the gaps when it is vulcanized by heating. For example, the thermosetting highly foaming sealer is used for filling an inside of a center pillar of an automobile in order to minimize wind whistles.
2. Discussion of the Background
An inside of a center pillar of an automobile is a hollow or a gap so that wind whistles may sometime generate during driving. It is effective to fill the gap in order to minimize the wind whistles. A urethane foamed substance or a rubber foamed substances is used for the purpose. The filling operation is generally performed by inserting the foamed substance into the gap through a hole for inserting the foamed substance during assembling processes.
Japanese Unexamined Patent Publication (KOKAI) No. 62882/1987 discloses a foaming sealer mainly composed of unvulcanized rubber. This foaming sealer is bonded on one of two parallel planes forming a gap, and heated at a temperature of 140.degree. C. to 170.degree. C. The foaming sealer is foamed and vulcanized by heating, and its volume is expanded to 1.3 to 1.6 times of the original volume. Thus, the gap is filled with the foamed foaming sealer.
The foaming sealer of Japanese Unexamined Patent Publication (KOKAI) No. 62882/1987 has been known that it is appropriate for securely sealing the gap and has a good filling property. As shown in FIGS. 17 and 18, the foaming sealer 100 is used to seal a gap 400 formed between a roof 200 of an automobile body and a sun roof housing 200' of the automobile body. The unvulcanized foaming sealer 100 is provided in the gap 400 at a predetermined position. The foaming sealer is foamed and vulcanized when it is heated in a paint drying oven of an electrodeposited coating process, and the volume of the foaming sealer increases in the gap 400 to seal the gap 400. The foamed foaming sealer thus prevents dusts and water from intruding into the gap from environment.
When filling the gap with the conventional foamed substance by inserting it through the inserting hole, a filling condition of the filled gap varies depending on gap shapes. It is thus difficult to fill up the every nook and corner of the gap. Further, it is impossible to fill a confined space where no inserting hole can be provided. Furthermore, an operator may get hurt in his hands because inserting holes have edges formed by punching steel plates.
When the foaming sealer disclosed in Japanese Unexamined Patent Publication No. 62882/1987 is employed, problems mentioned above can be removed, and the confined space can also be filled up with the foaming sealer. However, this foaming sealer results in increasing material cost, because it only expands at most by a foaming magnification of 2, and because a large amount of the forming sealer is required to fill up a gap of a large space. The foaming sealer should be made thicker to fill up a gap with a large interval, but the foaming sealer with a large thickness runs down or even slips off on a vertical plane when it is bonded on the vertical plane and heated.
In addition, after the foaming sealer 100 is foamed by heating to seal the gap 400 formed between the roof 200 and the sun roof housing 200' as shown in FIGS. 17 and 18, the foaming sealer 100 comes to have many large cells in it. Accordingly, the foaming sealer 100 is likely to soak water, and steel plates of the roof 200 and the roof housing 200' in contact with the foaming sealer 100 may be rusted.